When a spirometer is used, a person breaths in and out of an air

When a person breaths in, the volume of air in the chamber , casusing the float to move

As the person breaths out, the volume of air in the chamber and the float goes

The float is attached to a which writes onto a peice of paper, so the breaths are recorded as and lines on the paper

water is preset so that when the person breaths out, the in the air is absorbed and doesn't go back into the chamber